Navigation Links
Why chromosomes never tie their shoelaces
Date:9/8/2010

In the latest issue of the journal Nature, Miguel Godinho Ferreira, Principal Investigator at the Instituto Gulbenkian de Cincia (IGC) in Portugal, lead a team of researchers to shed light on a paradox that has puzzled biologists since the discovery of telomeres, the protective tips of chromosomes: while broken chromosome ends generated by DNA damage (such as radiation or cigarette smoke) are quickly joined together, telomeres are never tied to each other, thus allowing for the correct segregation of the genetic material into all cells in our body. Since telomeres erode in response to the continuous cell divisions in our body, this protective function fades away as we grow older. Complete loss of telomeres results in sticky chromosome-ends that join to each other creating to genetic chaos the very initial steps of cancer. Understanding how the tips of the chromosomes are protected from DNA repair and how the cells respond when they are unprotected will provide insights into the initial stages of tumourgenesis, ageing and future therapeutic interventions.

Cells respond to broken or damaged DNA by arresting their cell cycle while the damage is repaired. If the tips of chromosomes were recognized as broken DNA, cells would be constantly trying to mend the ends of chromosomes, leading to cell death and mutations in the DNA. Telomeres - the caps made up of protein and DNA at the tips of chromosomes - stop this from happening.

Through a series of meticulous experiments the Portuguese team, in collaboration with researchers at University of Illinois, Chicago, reveal that the crux lies in the changes of a protein, a Histone modification, located close to the telomeres. Histones are found along the entire length of all chromosomes, helping to package the DNA and also playing a role in regulating gene activity. Using fission yeast (used to make bread and beer) as a model organism, the researchers found that one of the Histones neighbouring the telomeres lacks a chemical signal, thus rendering the DNA damage recognition machinery incapable of arresting the cell cycle.

Says Miguel Godinho Ferreira, 'It's amazing, but it appears to be this single change that underlies the cell's ability to distinguish the end of the chromosome (i.e. a telomere) from a break in the middle. Indeed, along the rest of the genome, these Histones retain the chemical signal, so that when DNA damage does occur in any of these regions, DNA repair is set up and broken ends joined together.'

Telomeres are like the plastic caps on shoelaces: just as a shoelace starts unravelling when the cap is lost, so chromosome ends would become shorter with each cell division were it not for the telomeres. Telomeres are added or elongated by the enzyme telomerase. However, most cells in our body lack telomerase from when we are born, consequently telomeres become shorter and lose protection, sending signals for cells to stop dividing and start ageing. In about 85% of cancers, cells re-activate telomerase, contributing to their ability to divide and proliferate.

Even though DNA repair must be prevented at telomeres, assembly of the DNA damage recognition machinery is vital for telomerase activation and telomere elongation. Miguel Godinho Ferreira adds, 'Eukaryotic cells have evolved a very specific mechanism whereby telomerase recruitment goes ahead undisturbed, yet the whole DNA repair process is kept at bay from chromosome ends. Knowing the details of telomere capping is crucial to understanding its relationship to cancer, ageing and several diseases, and the multiple ways in which telomere manipulation may, potentially, lead to effective treatments".

He continues emphasizing the importance of fundamental basic research: "When Liz Blackburn, Carol Greider and Jack Szostak discovered telomerase and telomeres in the 80s, for which they got last year's Nobel Prize in Physiology or Medicine, they were searching for a solution to the "end-replication problem" and far from imagining the clinical implications these findings are currently developing. They were simply solving an academic puzzle created by the discovery of the double helix and the inability of DNA polymerases to synthesize the ends of linear DNA. Likewise, we are honored and excited to contribute to unravel these mechanisms, but perfectly aware that the direct implications of this work are still many years away".


'/>"/>

Contact: Silvia Castro
sacastro@igc.gulbenkian.pt
351-214-464-537
Instituto Gulbenkian de Ciencia
Source:Eurekalert  

Related medicine news :

1. Infectious Virus Hides In Human Chromosomes During Latency And Can Be Passed From Parents To Their Children
2. Womens Chromosomes May Affect Blood Pressure
3. Enterprise PDM Integration has Never Been Easier; Zero Wait-State Announces Leading SolidWorks Reseller GoEngineer as Master Distributor for DesignState
4. Gene is linked to lung cancer development in never-smokers
5. Business Book Author is Breaking All the Rules and Utilizing Social Media in a Way that Has Never Been Done Before
6. Ross Nanotechnology Corporation Introduces the NeverWet™ Coating on its First Consumer Product – The Clear-n-Clean Plunger
7. Global Basecamps Launches New Website: Researching and Booking Sustainable Travel Has Never Been Easier
8. Revolutionary Sports Bottle Unscrews at Both Ends for Easy Cleaning -- Never Deal With Stinky, Moldy Bottles Again
9. 1 in 4 Californian children have never seen a dentist, study finds
10. Phonak Asks Young FM Users to Tell Their Stories on YouTube
11. Luth Researchs IndicatorEDG(TM) Study Finds Americans Hopes of Achieving Their Dreams Are Fading
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Why chromosomes never tie their shoelaces
(Date:12/2/2016)... CA (PRWEB) , ... December 02, 2016 , ... For over twenty-four years, Doctors ... basis to help personal injury victims find high quality medical care. When the company ... Angeles area. Fast forward to present day and the now ten-page directory features a ...
(Date:12/2/2016)... ... 02, 2016 , ... Center for Autism and Related Disorders (CARD) Portland today ... spectrum disorder (ASD) and other developmental disabilities. The group, which is being launched with ... caregivers the opportunity to share stories and advice, seek help, and continue their education ...
(Date:12/2/2016)... ... December 02, 2016 , ... ... of two ostomy patients, standing as living proof that attitude and determination can ... diseases and issues that spike around the holidays. This campaign will offer patients ...
(Date:12/2/2016)... Wilmington, Delaware (PRWEB) , ... December 02, 2016 ... ... has released a new version of its SaaS LIMS, CloudLIMS Lite. CloudLIMS Lite ... from sample entry through labeling, storing, shipping and disposal. The new version is ...
(Date:12/2/2016)... ... ... Rijuven Corp launches rejiva ( http://www.rejiva.com ), a unique wearable technology that ... technology on the market can deliver all that rejiva can. , “Rejiva promotes relaxation ... health than the usual heart rate and steps taken”, adds Evens Augustin, CEO of ...
Breaking Medicine News(10 mins):
(Date:12/2/2016)... Research and Markets has announced the addition ... Demand Forecast to 2022" report to their offering. ... , , The ... and it is expected to grow at a CAGR of 5.5% during ... faster growth during the forecast period, a CAGR of 8.8% in the ...
(Date:12/2/2016)... , Dec. 2, 2016 Quantum Radiology,s Mobile ... expert radiologist interpretation directly to women at the workplace, ... corporations, such as Delta Air Lines and SunTrust Bank, ... as a component of wellness initiatives. "I ... SunTrust. It enables them to have a mammogram without ...
(Date:12/2/2016)... 2016 In the first ever attempt to ... derived from C. sativa, the Hebrew University in Jerusalem, ... Federico II , the Universita` del Piemonte Orientale and ... integrated and unified inventory of phytocannabinoids of different botanical ... the remarkable chemical and structural diversity of phytocannabinoids. As ...
Breaking Medicine Technology: